The inspection of baggage and/or other cargo at transit points such as airports and shipping ports has become almost universally mandatory. Luggage or cargo can be used for illegal transportation of contraband such as explosives, weapons, narcotics and dangerous chemicals. This warrants a rapid and accurate inspection system for determining the presence of concealed illegal materials.
X-ray scanning systems are the most widely used detection systems that provide for efficient inspection without the need for opening baggage. In conventional X-ray baggage systems, X-ray beams are directed through baggage as it is moved on a conveyor belt in a horizontal direction. The X-rays that have passed through the baggage are then processed for display on a video monitor to provide images of the contents of the baggage.
In general, conventional X-ray inspection systems work well within indoor environments, such as at airports. Conventional inspection systems, however, are also employed at ports, border crossings and customs checkpoints and/or sports venues, where space for housing and structures are not readily available. Thus, the ability of a system to operate outdoors becomes an important consideration.
Several components of conventional X-ray baggage systems are readily susceptible to damage when operating in inclement environments. For example, if a baggage inspection system is deployed in maritime environments such as a naval port, it must be able to endure the rigors of rain, sleet, salt spray and salt fog during operation.
These inclement weather elements could cause structural damage to conventional radiation shielding for the X-rays, thereby rendering the system hazardous to operate. Other parts of an X-ray inspection system that can be damaged due to moisture, humidity, dust and extreme temperatures, including the X-ray tube assembly and the collimator, which may alter the emission and scattering of X-rays, and the motors. In this case, not only the imaging quality of the system is adversely affected, but it also becomes electrically unsafe and unreliable.
Although most baggage inspection systems have a shielded housing for the X-ray tube, this alone is not sufficient to ensure unhindered functioning of the system in adverse weather conditions.
Attempts at improving the functioning of X-ray detection systems have largely focused on compensating for the effects of environmental factors on the system's detection capability. For example, U.S. Pat. No. 5,970,113 discloses a CT scanning system having a radiation source for directing radiation through a region and an array of detectors for receiving radiation from the region while scanning the region and for generating detector signals indicative of the received radiation, a method of compensating for electrical currents that are generated by the detectors independently of radiation received by the detectors, said method comprising: generating a calibration relationship for the array of detectors, said generating comprising: varying the temperature of the array of detectors, measuring the electrical currents generated by the detectors as the temperature of the detectors is varied, characterizing the variation in the electrical currents with temperature, using the variation in the electrical currents with temperature, generating a set of first detector offset signals to be applied to the detector signals generated while scanning the region; after generating the calibration relationship, sensing a first temperature of the array of detectors; measuring a first updated detector offset signal associated with the first temperature; scanning the region to generate a detector signal; sensing a second temperature of the array of detectors; using the second temperature, the calibration relationship, and the first updated detector offset signal, adjusting the first updated detector offset signal to generate an adjusted detector offset signal such that the adjusted detector offset signal is based on the first updated detector offset signal, the second temperature and the calibration relationship; and applying the adjusted detector offset signal to the detector signal.
This abovementioned prior art system, however, does not address the potential structural and internal damage that a detection system can incur when operated in harsh weather conditions. Conventional prior art baggage inspection systems are thus presently limited in their ability to withstand the effects of unfavorable and inclement operating environments.
What is therefore needed is a baggage inspection system that is capable of delivering optimum threat detection performance when operated in inclement weather.
Since dust or moisture on the baggage itself may also harm an inspection system, what is also needed is a baggage inspection system that is designed to both withstand inclement weather conditions and remain substantially unaffected by the type of baggage being scanned.
What is also needed is a system that is designed for mobility.